The invention relates to an apparatus for calibration of a photosensor chip. The photosensor chip is equipped with a multiplicity of light-sensitive elements.
The invention also relates to a microscope having an apparatus for calibration of a photosensor chip. In this case, the microscope has at least one light source which emits an illumination light beam which illuminates a sample point-by-point, in the form of a point grid or line-by-line through the optics and via a scanning device, and having a dispersive element which spatially spectrally splits a detection light beam which originates from the sample, and directs it at a light-sensitive area on a photosensor chip.
The invention also relates to a method for calibration of a photosensor chip
German Patent Application DE 102 53 609 discloses a scanning microscope which has a detector, which is arranged in a detection beam path, for reception of detection light originating from a sample. An optical shutter means is arranged between the sample and the detector, and can be used to block the detection beam path. A control means is provided for open-loop control of the shutter means. The detection beam path can be blocked automatically outside the scanning process and when the detection light power is excessively high.
US Patent Application 2003/0223531 discloses the signal gain of a charge multiplication detector or of a CMD (Charge Multiplying Device) being checked with high precision. The CMD has a multiplicity of sections, each of which in turn represents one CMD, so that charge multiplication can be carried out in this way.
German Patent Specification DE 100 38 526 discloses a method and an arrangement for fluorescence microscopy, in particular for laser scanning microscopy, fluorescence correlation spectroscopy and scanning near-field microscopy, in order to investigate primarily biological samples, preparations and associated components. The changeover from the detection of a small number of broad spectral color fluorescence bands to the simultaneous recording of complete spectra opens up new capabilities for identification, separation and association of the generally analytical or functional sample characteristics with respect to three-dimensional structure elements or dynamic processes. Simultaneous investigations of samples with multiple fluorophores are thus possible with overlapping fluorescence spectra, even in three-dimensional structures with thick samples. The data recording rate is not reduced by the arrangement.
The German translation DE 690 32 582 T2 of a European Patent discloses a silicon avalanche photodiode matrix, which comprises a body composed of n-type silicon semiconductor material, which has phosphorous distributed uniformly in it by means of neutron conversion doping. The resistivity has a maximum discrepancy of 0.5% over at least one active area. The body has a first and second opposite surface, which enclose a radiation input surface, and which are separated from one another by a side surface. Furthermore, a p-n junction is provided and extends between the surfaces, with the side surface being inclined in order to maximize the breakdown voltage. A multiplicity of signal contacts which are arranged on the first body surface form the individual photodiodes. Furthermore, a common electrode is provided, and is arranged on the second body surface. A means for reading signals from the signal contacts is likewise provided.
The German translation DE 692 31 482 T2 of a European Patent discloses a CCD image sensor with small pixels. So far, the increasing demand in this field from the consumer market for CCD cameras with ever higher resolution requires that the developers increase the number of pixels of the CCD image sensors that are used in these products. At the same time, the competitive pressure requires not only for the price of these sensors to be maintained or to be reduced, but also for the chip size to be reduced, in consequence resulting in a reduction in the size of the active pixel area. However, this leads to two major problems: the reduction in the sensitivity of the image sensor, and the reduction in the signal-to-noise ratio. The sensitivity of the image sensors is proportional to the pixel area, to the aperture efficiency, to the quantum efficiency, to the integration type and to the charge/voltage conversion factor. The maximum sensor sensitivity of present-day image sensors is normally governed by the noise level of the charge detection amplifiers which convert the charge that has been collected to an output voltage. Without this restriction, it will be possible to detect the individual photons, and in consequence to achieve a photon counting mode, the maximum capability of an image sensor, which is governed by the fundamental laws of physics.
British Patent GB 2 348 070 discloses a photocathode CCD sensor having a separate high-field multiplication register. The imaging device is suitable for counting photons, or for applications in low lighting conditions. The apparatus comprises a CCD sensor, which is arranged in such a manner that it receives the electrons which are emitted from a photocathode. The CCD component has a separate high-field multiplication register, to which signals are transferred from an output register. The aim of this is to achieve a better signal-to-noise ratio, and better resolution.
German Patent Application DE 10 2004 003 993 discloses an apparatus for verification of the photons in a light beam which originates from a physically limited source, in particular for use in a fluorescence microscope. For this purpose, a detection device is provided in order to increase the maximum counting rate which can be processed by the detection device. The detection device comprises at least two detectors. A component is provided in the beam path of the light beam, by means of which the light beam is split in such a manner that the photons are distributed over the detectors, for verification purposes.
In the case of EMCCD chips, electrons that are generated by light in the photo-active area are amplified again in an amplifier register before they are read. The gain of this amplification register depends on various parameters, such as the voltage, temperature, time etc., in a complex manner. The data obtained about the illumination intensity of the EMCCD chips is correspondingly difficult to assess. Problems occur even if the EMCCD chip has a single amplification register (as is the normal case), and a plurality of measurements carried out successively are intended to be compared with one another. Particularly serious problems occur in particular when the EMCCD chip has a plurality of amplification registers, which may behave differently for various reasons.